Empires, the award winning Half-Life 2 mod, combines the best of the first person shooter and real-time strategy genres. Fight as either the Northern Faction, remnants of the fallen nation of Jekotia, or as the imperial Brenodi Empire. Empires features:

Just a bit of advice; tone down the bumpiness of the snow. Normally snow is quite flat rather than wrinkly, save when collected around areas or churned up a lot. Long story short: make another texture for 'flat' snow, blend it with the wrinkly snow and apply; where the snow has fallen untouched, it should be flat. Equally, more snow would build up in the shaded areas where the sun can't warm it up. Would just look so much better; the map's looking pretty awesome as-is, but the snow detracts from that quite badly.

Finally: more snow on top of the trees, and unless every plant there is evergreen, shouldn't most of them be bare rather than sprouting leaves?

Look up pictures of Moscow in winter, you'll get an idea of what I mean. Excellent work otherwise though!

Cgtextures.com or Cgtextures.com - take your pick. Already tiled, nice and 'smooth' snow, courtesy of CG Textures (obviously); all that needs doing is a size down to 512x512 and saving to vtf. The rest is just a quick .vmt file to set up the texture blend and then applying in Hammer... which would in itself be the longest part.